A conventional mechanical seal used between a motor and a product pump includes a stationary seal ring usually connected to the motor housing and a rotatable seal ring operably connected to the motor shaft. Each seal ring is provided with a lapped seal face opposing the seal face of the other ring thereby establishing a dynamic fluid tight seal therebetween. Resilient means such as coil springs or bellows urge one seal ring face toward the other in a sealing relation.
Most mechanical seals of the type described have a number of metal parts, such as the coil springs or bellows which are exposed to the pump fluid. In pumps wherein precipitates are emersed or included in the pump fluid, the precipitate matter readily accumulates and hardens about the seals and associated mounting parts and presents unique problems. That is, because of manufacturing tolerance buildup and other factors, the seal ring faces must be permitted a degree of flexure relative to one another during pump operation. The brittle-hard precipitate buildup around and about the seals and their mounting assembly, however, quickly immobilizes the seal faces. Accordingly, deterioration of the seal surfaces usually occurs and the seal fails.
In Baumler et al, U.S. Pat. No. 3,269,738 a glide ring seal for use with a rotary piston motor is disclosed. This patent describes the use of a disk-type spring for pressing a glide ring into an operative position. Unlike the present invention, however, the Baumler et al reference is silent concerning a method and means for mounting the seal assembly in a balanced state from the impeller side of the housing and through axially adjustable means.
In Voytek, U.S. Pat. No. 3,272,519 seals for use between rear wheels of a tractor and a tractor frame are described. Each seal uses a pair of elastomeric "rounded square" cross section, sealing elements for urging a pair of seal rings toward one another. During use, the elastomers are stressed and deform to a diamond shape. Such action leaves crevices at the concave grooves into which the elastomeric members are received to collect debris.
The Pechiney Company of France has also developed a seal called the "Cefilac" seal. Unlike the present invention, the Pechiney device has a resiliently mounted rotating seal assembly. As a skilled artisan will appreciate, the resilient mounting of the rotary seal requires that the static seal must be arranged with unerring accuracy with respect to the drive shaft. In such construction, the sealant assembly is not retrofittable to the pump. Instead, various pump parts must be machined to accept the Cefilac seal. As mentioned, such parts must be machined with a great degree of precision. Such a tolerance relationship is difficult to establish and even harder to maintain when seal replacement is required.